Digital video recorder (DVR) systems are becoming increasingly popular with consumers. Digital video recorder systems use magnetic hard disk drives rather than magnetic cassette tapes to store video programs. For example, the ReplayTV™ recorder and the TiVO™ recorder record television programs in digital formats on hard disk drives using, for example, MPEG-2 compression. Also, some DVR systems may record on a readable/writable digital versatile disk (DVD) rather than a magnetic disk.
One advantage that a digital video recorder system has over a conventional video cassette recorder is time-shifted viewing. Time shifting occurs when a user watches a live broadcast with a delay. This may occur, for example, when the user presses the Pause button on the DVR system to answer a phone call and a few moments later resumes viewing the live broadcast. During the pause period, the DVR system continues to record the live broadcast television (TV) program on the hard disk drive, but the screen is frozen at the part of the TV program where the Pause button was pressed. When the user presses the Pause button again (or, alternatively, presses the Play button), the DVR system plays back the recorded TV program from the disk drive from the point at which the TV program was paused.
In this manner, the user views the live broadcast program with some delay period. The user may catch up to the live broadcast by pressing Fast Forward (which plays stored video back at faster than normal speed) or by pressing Skip (which skips sections of stored video). However, if the user continues to watch the delayed TV program at normal speed and does not catch up to the live broadcast, the live TV program continues to be recorded to the disk drive and then played back.
However, when a file system is used to control the disk drive, each recorded television program is saved as a data file on the disk drive. Unfortunately, conventional file management techniques are inefficient when it comes to time-shifted viewing. This is because the file management system must simultaneously write (store) the live broadcast to the data file and read (retrieve) the delayed television program from the data file.
There is therefore a need in the art for an improved digital video recorder (DVR) system capable of time-shifted viewing. In particular, there is a need for a digital video recorder (DVR) system having a file management system that can efficiently implement time-shifted viewing.